Automatic dishwashing machine with soak cycle



Dec. 22, 1-910 KERR ETAL 3,549,294

AUTOMATIC DISHWASHING MACHINE WITH SOAK CYCLE' Filed March 25, 1970 FIG -3 TIME CYCLE CHART o 5 no I5 SOMIN.

AIN

SOAK

K BYPASS LINE SW. BYPASS PUMP CAM BYPASS FIG-4 AUX. TIMER CHART A INVENTOR 5 PROGRAM SELECTOR SWITCH s CYCLE CONTACTS CLOSED ROBERT R. KERR 8: FULL A B D y BEN J. VALLOR SOAK A c 0 RINSE-HOLD B o A TTORNEYS United States Patent 3,549,294 AUTOMATIC DISHWASHING MACHINE WITH SOAK CYCLE Robert R. Kerr and Ben J. Vallor, Troy, Ohio, assignors to The Hobart Manufacturing Company, Troy, Ohio, a

corporation of Ohio Filed Mar. 25, 1970, Ser. No. 22,578 Int. Cl. 150% 3/02 US. Cl. 134-58 Claims ABSTRACT OF THE DISCLOSURE A tank defines a wash chamber in which racks are positioned for supporting articles having baked-on food soils. A motor driven timer system automatically controls the mechanical components of the machine including a fill valve for supplying water to the chamber, a wash pump for recirculating and spraying the water onto the, articles and a drain pump for removing the water, according to a plurality of selectable predetermined cycles. One of the selectable cycles consists of a soak cycle Where the water is combined with a cleaning compound to form a cleaning solution which is sprayed onto the articles. The wash pump is then deenergized for approximately twelve minutes to eifect static soaking of the solution into the baked-0n food soils on the articles. Following the soak period, the wash pump is reenergized along with the drain pump to flush the food soils from the articles and to remove the soils from the chamber with the solution. This soak period is followed by pro-rinse, wash, rinse and dry periods which may also be selected without the soak period.

BACKGROUND OF THE INVENTION In order for an automatic commercial or domestic dishwashing machine to be used effectively for assisting the cleaning of heavily soiled articles such as pots and pans having baked-on food soils, it is common to preclean each article by either manually scrubbing the article or by soaking the article in a volume of water. After the bulk of the baked-on foods is removed by the manual scrubbing or the submerged soaking operation, the automatic dishwashing machine is used to remove the remaining portions of the food soils and to sanitize the articles.

It has been determined that a variety of baked-on food soils can be removed from food preparation and serving articles by spraying the articles with a solution of water and a cleaning compound and by permitting the solution to soak into the food soils so that they can be flushed from the surfaces of the articles. It has also been found important for the articles sprayed with the cleaning solution to be maintained in a humid environment to prevent evaporation of the solution from the surfaces of the articles.

SUMMARY OF THE INVENTION The present invention is directed to an improved automatic dishwashing machine which provides for selecting different washing cycles, one being a soak cycle which is elfective to remove heavy food soils which have been baked-on food preparation and serving dishes, utensils and other articles. In accordance with a preferred em bodiment, the dishwasher of the invention includes an automatic timer system and a program selector switch which provides for selecting either a normal cycle including pre-rinse, wash, rinse and dry periods or a soak cycle which efiects a soaking period prior to the normal cycle.

When the soak cycle is selected, the timer system actuates a solenoid fill valve in the hot Water supply line and also actuates the drain system to purge the supply line and assure that a charge of hot water is supplied to the wash chamber of the machine. A granulated cleaning compound is added to the water within the chamber, and the timer system actuates a main recirculating pump which sprays the solution of water and cleaning compound onto the soiled articles supported by racks within the wash chamber.

The timing system then deenergizes the recirculating pump for a period of approximately twelve minutes to efiect static soaking of the solution into the baked-on food soils on the articles and causing a breakdown of the soils. The solution is retained within the sump of the wash chamber during the soaking period after which the main recirculating pump is reenergized along with the drain pump causing the food soils to be flushed from the articles and to be drained from the wash chamber with the cleaning solution. The soaking period is followed by a series of wash, rinse and dry periods to complete the cycle. If the articles to be cleaned are not soiled with baked-on foods, the soak cycle may be bypassed simply by selecting the normal or full cycle causing the dishwashing machine to operate through only a series of wash, rinse and dry periods.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of a front loading dishwashing machine incorporating a timer control system constructed in accordance with the invention;

FIG. 2 is a schematic wiring diagram of the timer control system employed in the dishwashing machine shown in FIG. 1;

FIG. 3 is a chart illustrating the sequence of operation of the main control timer;

FIG. 4 is a chart illustrating the operation of an auxiliary timer; and

FIG. 5 is a chart showing the different cycles of the dishwashing machine and the positions of the corresponding selector switches for producing the cycles.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a front loading automatic dishwashing machine including an outer cabinet 10 enclosing a tank 11 having a bottom 12 and defining a wash chamber 14. A door 15 provides access to the wash chamber 14 and is pivotable between a horizontal open position and a vertically closed position where the door is secured by a centrally located latch 16 such as disclosed in Pat. No. 3,328,062 which issued to the assignee of the present invention. A set of vertically spaced racks -17 are supported by corresponding tracks within the chamber 14 and are movable to positions extending over the open door 15.

The bottom 12 of the tank 11 slopes downwardly toward the center so that water collecting thereon drains into a sump 18 in which is mounted a main recirculating pump 20 driven by a motor 22 for recirculating the water through a reaction spray arm 24 over the soiled articles placed within the racks .17. A drain pump 25 is mounted directly below the sump .18 and is also driven by the motor 22. The drain pump 25 has an outlet connected to a drain line 26 having a normally closed solenoid actuated drain valve 27. A more detailed description of the wash system is disclosed in Pat. No. 3,323,529 which issued to the assignee of the present invention.

Referring to FIG. 2, a program selector switch 30 is mounted within the upper portion of the door 15 on one side of the latch 16 and includes a series of single pole, single throw push button switches A-D which provide for selecting either a full or normal cycle, a soak cycle or a rinse and hold cycle as indicated on the chart of FIG. 5. Also located within the upper portion of the door 15 is a main timer 35 having a series of single pole, double throw switches E-I which are actuated by corresponding cams mounted on a common shaft driven by a main timer motor 36. An interior dial 38 is also connected to rotate with the time shaft and is located adjacent the upper portion of the door 15.

7 Referring to FIG.- 2, power is supplied to the timer control system through power lines L1 and L2, and line L2 is connected to one side of program selector switch D through a door interlock switch 42 which closes in response to actuation of the latch 16 to its closed position. The other side of program selector switch D is connected to the top contact of cam actuated timer switch I and also to one side of a line switch I which is closed in response to axial movement of the main timer cam shaft produced by closing of the door latch 16 and is opened by an axial camming movement of the shaftduring the final increment of rotation of the shaft. The other side of line switch I and the common contact of timer switch I are connected to one side of program selector switches B and C. A pilot light 43 is also connected across line L1 and the common contact of selector switches B and C. The bottomcontact of timer switch I connects with the pump motor 22 and also to the bottom contact of timerswitch F by a jumper 44.

The top contact of timer switch F connects with a blower 45 arranged in parallel with a series connection of a thermal protector switch 46 and a heating element 48 located within said blower housing. In a conventional manner, the blower 45 and the heating element 48 function to provide drying of the articles within the wash chamber by directing a flow of warm air over the articles. The common contact of timer switch F and the common contacts of timer switches E and G connect to the top contact of timer switch H and to one side of program selector switch A. The other side of selector switch A is connected to the common side of selector switch B and to the main timer motor 36.

The top contact of timer switch E connects to a solenoid fill valve 52 through a water level pressure safety switch 53. The bottom contact of timer switch E is connected to an electrically actuated rinse agent dispenser 55 mounted within the door 15. The top contact of timer switch G connects with an electrically actuated detergent cup or dispenser 58, and the bottom contact of timer switch Gi's connected to the solenoid drain valve 27. The right oropposite side of program selector switch C connects with the common contact of timer switch H.

The top contact" of timer switch H also connects with one side of a cam actuated switch K of an auxiliary timer 60 which is located within the dishwashing machine cabinet below the bottom 12, but may be located within the door 15. The other side of switch K is connected with the bottom contact of main timer switch H and to a motor 62 for driving the cam shaft of the auxiliary timer 60. As shown in FIG. 2, line L1 is connected directly to the fill valve 52, rinse agent dispenser 55, blower 45, detergent dispenser 58, drain valve 27, auxiliary timer motor 62, main pump motor 22, main timer motor 36 and the pilot light 43.

In reference to FIGS. 4 and 5, when the full or normal cycle push button is depressed, switches A, B and D close, and the cycle of operation progresses through two prerinse periods, a wash period, two rinse periods and a dry period, as shown by the time chart in FIG. 3. Since program selector switch C remains open, timer switch H has no effect on the operation of the dishwashing machine. At the end of the full cycle, selector switches A, B and D remain closed until the latch 16 is actuated to open the door 15. The actuation of the latch 16 operates a cancel bar within the program selector switch causing switches A, B and D to open.

When'the rinse-hold push button is depressed, programmed selector switches B and D close so that the main timer motor 36 is energized through switches D, J and B. The fill valve 52 and drain valve 27 are energized through switches D, J, I and F. In addition, pump motor 22 is energized through switches D, J and I. When timer swi ch I-opens at the end of four minutes (FIG. 3), the timer motor 36 remains energized for four additional minutes. The pump motor 22 and drain valve 27 are then energized for one minute to drain the machine. Then only the timer motor 36 remains energized until the end of the cycle when line switch I is cammed open in response to axial movement of the timer shaft by a pin (not shown) extending through the shaft and engaging a'ramp formed on the end wall of the timer.

In accordance with the present invention, when it is desired to use the dishwashing machine for cleaning articles having heavy baked-on food soils, the push button for the soak cycle is depressed causing program selector switches A, C and D to close and the main timer motor 36 to be energized through switches D, J, C, H and A.

, During the first three minutes of the cycle, the fill valve 52 is energized. The drain valve 27 is energized to an open condition for the first minute of the cycle so that the water supply line is purged thereby assuring that only hotwater is flowing into the wash chamber before the drain valve 27 closes.

The main recirculating pump motor 22 is also energized during the first four minutes of the cycle causing the hot water to be recirculated and combine with a granulated cleaning compound supplied to the wash chamber before the door 15 is closed. The solution of water and cleaning compound is sprayed onto the soiled articles within the racks 17, and at the endof four minutes of the cycle, timer switch H deenergizes the main time motor 36 and energizes the motor 62 of the auxiliary timer 60.

Referring to FIG. 4, after the motor 62 of auxiliary timer 60 has been energized for thirteen minutes, switch K closes thereby reenergizing the main timer motor 36 through switches C, H and A. During this thirteen minute period when only the pilot light 43 and the auxiliary timer motor 62 are energized, the cleaning solution soaks into or penetrates the heavy food soil on the articles and breaks down the soil so that after the soaking period, the food soils will be flushed from the articles'and drained from the wash chamber when the main recirculating pump motor 22 is reenergized with cleaning solution or with fresh water and the drain valve 27 is reenergized. Following the soak period, the cycle continues in the same manner as the full cycle and as indicated in the chart of FIG. 3. After the auxiliary timer motor 62 is energized fifteen minutes, timer switch K opens thereby resetting the auxiliary timer 60 for the next soak cycle.

From the drawing and the above description, it is apparent that an automatic dishwashing machine incorporating a timer control system constructed in accordance with the invention, provides desirable features and advantages. For example, by incorporating a soak cycle wherein a hot water cleaning solution is permitted to soak statically into the food soils on the articles for a period of at least three to five minutes and preferably for a period of between ten and fifteen minutes, while the articles are enclosed within a high humidity chamber, it has been found that extremely heavy baked-on food soils will be released from the articles so that a subsequent flushing of a hot water cleaning articles with the solution or fresh water is effective to remove the food soils from the articles. Thus the automatic dishwashing machine becomes substantially more effective in cleaning pots and pans and other food preparation articles which commonly have heavy baked-on food soils. While most of the commercially available detergents for automatic dishwashing machines have proven satisfactory as a cleaning compound for use during the soak cycle, an enzyme detergent manufactured and sold by Economics Laboratory under the trademark Pan Dandy has proven especially effective for releasing many food soils.

Another important feature is provided by the auxiliary timer 60. That is, when the soak cycle is selected, and switches A, C and D are closed, timer switch H cooperates with the auxiliary timer 60 to provide the thirteen minute dwell of the main timer so that the cleaning solution has sufficient time to penetrate the heaviest of baked-on food soils. It is to be understood, however, that the thirteen minute dwell during the soak period may also be obtained by a timer incorporating a rapid advance motor such as disclosed in Pat. No. 3,125,105 which issued to the assignee of the present invention. That is, the main timer could be programmed for the soak cycle including the thirteen minute soaking period. If a cycle other than the soak cycle was selected, the rapid advance motor would be energized at the beginning of the soaking period for quickly by-passing the soaking period.

While the form of dishwashing machine herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of machine, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims. For example, it is within the scope of the invention to include a heating element in the sump of the wash chamber 14 and to provide control means for energizing said heating element during the soak period to assure maximum humidity Within the chamber 14. It should be noted that it is conventional to provide a heating element in the sump of the wash chamber of a dishwasher for heating water during other portions of the cycle and such conventional element could be used in the manner just described to assure maximum humidity during the soak period. It is also possible to re-energize the main recirculating pump momentarily during the soak cycle to effect flushing of a portion of the heavy baked-on soils from the articles and then subsequent soaking of the remaining portion of the soils. However, with presently available cleaning compounds, this interrupted soaking cycle has not been found necessary. Moreover, it is within the scope of the invention to drain the solution from the sump 18 during or at the end of the soak period and to refill the sump 18 with fresh water so that when the rinse pump is re-energized the soil is flushed from the articles with fresh water.

What is claimed is:

1. In an automatic dishwashing machine including a tank defining a Wash chamber,

rack means within said chamber for supporting articles having food soil thereon,

means for supplying Water into said chamber for combining with a water soluble cleaning compound to form a cleaning solution,

means for recirculating said solution to effect spraying of said solution onto the articles supported by said rack means, means for draining said solution from said chamber,

a program timer control system having means for controlling said water supplying means to introduce a predetermined volume of water within said chamber, means for controlling said recirculating means to spray said solution onto the articles Within said chamber, and means for controlling said draining means to drain said solution from said chamber,

the improvement wherein said timer control system comprises:

means for deenergizing said recirculating means after the articles are sprayed with said solution, means for maintaining said recirculating means deenergized for a continuous period of at least five minutes to hold said solution in continuous static contact with the articles to cause effective static soaking of said solution into the food soil on the articles, means for reenergizing said recirculating means after said period and means for actuating said drain controlling means for draining said cleaning solution from said chamber.

2. A dishwashing machine as defined in claim 1 wherein said means for maintaining said recirculating means deenergized is efiective to maintain said recirculating means deenergized for a continuous period of at least ten minutes during said soaking period.

3. A dishwashing machine as defined in claim 1 including a plurality of manually actuated cycle selecting switches, said timer control system comprises a plurality of cam actuated switches, and circuit means connecting at least two of said manually actuated switches in series with at least one of said cam actuated switches during the soaking period.

4. A dishwashing machine as defined in claim 1 wherein said timer control system further includes a selectable control means for bypassing said means for deenergizing said recirculating means for at least live minutes and the corresponding soaking period when the articles are not heavily soiled.

5. A dishwashing machine as defined in claim 1 wherein said controlling means for said draining means is effective to hold said solution within said chamber during sad static soaking period to assure a humid environment within said chamber.

6. In an automatic dishwashing machine including a tank defining a wash chamber,

rack means within said chamber for supporting articles having food soil thereon,

means for supplying water into said chamber for combining with a water soluble cleaning compound to form a cleaning solution,

means for recirculating said solution to effect spraying of said solution onto the articles supported by said rack means, means for draining said solution from said chamber,

a program timer control system having means for controlling said water supplying means to introduce a predetermined volume of Water within said chamber, means for controlling said recirculating means to spray said solution onto the articles within said chamber, and means for controlling said draining means to drain said solution from said chamber, and said timer control system being effective to produce a sequence of operations including a first washing period with said cleaning solution, a subsequent main washing period with said cleaning solution followed by at least one rinsing period with fresh water,

the improvement wherein said timer control system comprises:

means for energizing said recirculating means during said first washing period for a time sufiicient to spray said solution on the articles, means for deenergizing said recirculating means during said first washing period after the articles are sprayed with said solution, means for maintaining said recirculating means deenergized during said first washing period for a total time of at least five minutes to hold said solution statically on the articles to cause eifective static soaking of said solution into the food soil on the articles and loosening of the food soil, means for subsequently reenergizing said recirculating means with said cleaning solution in said chamber to remove loosened food soil from the articles, means for actuating said drain controlling means for draining said cleaning solution from said chamber, and means for subsequently efi'ecting said rinsing period to remove said cleaning solution and any remaining loosened food soil from the articles.

7. In an automatic dishwashing machine including a tank defining a wash chamber,

rack means within said chamber for supporting articles having food soil thereon,

means for supplying water into said chamber for combining with a water soluble cleaning compound to form a cleaning solution,

means for recirculating said solution to effect spraying of said solution onto the articles supported by said rack means, means for draining said solution from said chamber,

a program timer control system having means for controlling said water supplying means to introduce a predetermined volume of water within said chamber, means for controlling said recirculating means to spray said solution onto the articles within said chamber, and means for controlling said draining means to drain said solution from said chamber, and

said timer control system being efiective to produce a sequence of operations including a washing period with said cleaning solution followed by at least one rinsing period with fresh water,

the improvement wherein said timer control system comprises:

means for energizing said recirculating means during said washing period for a predetermined time sufficient to spray said solution on the articles, means for deenergizing said recirculating means during said washing period after the articles are sprayed with said solution, means for maintaining said recirculating means deenergized during said washing period for a continuous time greater than said predetermined time to hold said solution statically on the articles to cause eifective static soaking of said solution into the foodsoil on the articles and loosening of the food soil, means for subsequently reenergizing said recirculating means for a substantial time with said cleaning solution in said chamber to remove the loosened food soil from the articles and means subsequently actuating said drain controlling means for draining said cleaning solution from said chamber.

8. In an automatic dishwashing machine including a tank defining a wash chamber,

rack means within said chamber for supporting articles having food soil thereon,

'means for supplying water into said chamber for combining with a water soluble cleaning compound to form a cleaning solution,

means for recirculating said solution to efiect spraying of said solution onto the articles supported by said rack means, means for draining said solution from said chamber, v

a program timer control system having means for controlling said water supplying means to introduce a predetermined volume of water within said chamber, means for controlling said recirculating means to spray said solution onto the articles within said chamber, and means for controlling said draining means to drain said solution from said chamber, and

said timer control system 'being effective to produce a sequence of operations including a washing period with said cleaning solution followed by at least one rinsing period with fresh water,

the improvement wherein said timer control system comprises:

means for energizing said recirculating means during saidwashing period for a predetermined time period sufficient to spray said solution on the articles, means for deenergizing said recirculating means during said washing period after the articles'are sprayed with said solution, means for maintaining said recirculating means deenergized during said washing period for a total time of at least five minutes to hold said solution in static contact with the articles to cause eifective static soaking of said solution into the food soil on the articles, means for subsequently energizing said recirculating means with said cleaning solution in said chamber for a time period greater than said predetermined time period and means for subsequently actuating said drain controlling means for draining said cleaning solution from said chamher.

9. A dishwashing machine as defined in claim 8 wherein means for maintaining said recirculating means deenergized is elfective to maintain said recirculating means deenergized for a continuous period of at least ten minutes during said soaking period.

10. A dishwashing machine as defined in claim 8 wherein said timer control system comprises a main timer and an auxiliary timer each having a motor, and circuit means for deenergizing said motor of said main timer and entrgizing said motor of said auxiliary timer during said soaking period.

References Cited UNITED STATES PATENTS 2,151,354 3/1939 Osuch l3457X 2,385,264 9/1945 Ferris 134-25 2,600,541 6/1952 Johnson 134171X 2,664,094 12/1953 Spragins 134-95X 2,710,819 6/1955 Weber et al. 134-23 3,049,133 8/1962 Jacobs 134-57 3,063,459 11/1962 Jacobs l3458 3,125,105 3/1964 Geiger l3458 3,183,120 5/1965 Mori 134-7 3,456,462 7/1969 Schaverien l3457X 3,498,304 3/ 1970 Rumbaugh 134--58 2,676,598 4/1954 Bowersox l3456(D) 3,384,098 5/1968 Swetnam l3458 (D) FOREIGN PATENTS 1,307,875 9/ 1962 France 134-57 ROBERT L. BLEUTGE, Primary Examiner US. Cl. X.R.

52 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,549,294 Dated December 22, 1970 Inventor) Robert R. Kerr and Ben J. Vallor It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

released from the articles so that a subsequent flushing of the articles with a hot water cleaning solution or fresh water is effective to remove the food soils from the articles. Thus the automatic dishwashing machine becomes-- Column 6 line 19, "sad" should be "and".

Column line 8 after "means" insert for Column 8, line 27, "energizing" is misspelled.

Signed and sealed this 11th day of May 1971 (SEAL) Attest:

Column 4, cancel lines 59-62 and rewrite as follows:

EDWARD M.FLETCHER,JR. WILLIAM B. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

